- LLYWELYN EIN LLYW OLAF - see LLYWELYN ap GRUFFYDD
- LLYWELYN FARDD (fl. c. 1150-1175), poet
- LLYWELYN FAWR (fl. early 13th century), lords of Merioneth
- LLYWELYN FAWR - see LLYWELYN ap IORWERTH
- LLYWELYN (fl. early 13th century) - see LLYWELYN FAWR
- LLYWELYN FYCHAN ap LLYWELYN ab OWAIN FYCHAN (d. c. 1277), lord of Mechain
- LLYWELYN GOCH ap MEURIG HEN (fl. c. 1360-1390), poet
- LLYWELYN GOCH Y DANT (fl. 1470-1471), bard
- LLYWELYN - see LLYWELYN ap IORWERTH
- LLYWELYN - see LLYWELYN ap SEISYLL
- LLYWELYN (d. 1282) - see LLYWELYN ap GRUFFYDD
- LLYWELYN SION (fl. second half of the 16th century), poet, farmer, at one time beadle or crier in the courts, a professional copyist by trade, and one of the most important figures in the literary life of Glamorganshire
- LLYWELYN Y GLYN - see LEWIS GLYN COTHI
- LLYWELYN, TOMAS (fl. c. 1580-1610), bard and gentleman
- LLYWELYN-WILLIAMS, ALUN (1913 - 1988), poet and literary critic
- LORT family Stackpole,
- LOUGHER, Sir LEWIS (1871 - 1955), industrialist and politician
- LOUGHER, ROBERT (d. 1585?), civil lawyer and ecclesiastical administrator
- LOVE, CHRISTOPHER (1618 - 1651), Presbyterian minister
- LOVEGROVE, EDWIN WILLIAM (1868 - 1956), schoolmaster and an authority on Gothic architecture
- LOVELAND, KENNETH (1915 - 1998), journalist and music critic
- LOWE, RICHARD (1810 - 1853), weaver and musician
- LOWE, WALTER BEZANT (1854 - 1928), antiquary
- LOYD, LEWIS (1767 - 1858), banker
- LOYD?, SAMUEL (1796 - 1883), banker - see LOYD, LEWIS
- LUCAS, RICHARD (1648 - 1715), cleric and author
- LUMLEY, RICHARD (1810 - 1884), Calvinistic Methodist minister
- LYNE, HORACE SAMPSON (1860 - 1949), president of the Welsh Rugby Union, 1906-1947
- LYNN-THOMAS, Sir JOHN (1861 - 1939), surgeon